Geometry Boost List: Re: [geometry] 3D Coordinate Systems types - right-handed vs left-handed (and confusing rotate_transform)

Subject: Re: [geometry] 3D Coordinate Systems types - right-handed vs left-handed (and confusing rotate_transform)
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 2015-10-08 16:23:44

Hi Hussein,

Hussein Almashouq wrote:
> Hi to all,
>
> I wonder is how  boost geometry  models 3d points and boxes using 
> which 3D coordinate systems convention  Left or Right-handed ?
>
> https://www.evl.uic.edu/ralph/508S98/coordinates.html

 From the user's perspective I think this shouldn't be important. I may 
be missing something but I think that currently in Boost.Geometry the 
only place where this could be noticeable is transform() with 
rotate_transformer. It only supports 2D case though.
What exactly would you like to do with Points and Boxes?

Internally in the library we're calculating e.g. cross products in some 
cases, for instance in spherical side formula, there is also also 
cross_product() function in extensions. Therefore I always thought that 
internally we're using right-handed coordinate system, with angles 
increasing counter-clockwise. Surprisingly the rotate_transformer 
rotates geometries clockwise. It's even more confusing because in the 
comment there is a link to the wikipedia page and there the 
counter-clockwise rotation is presented. Am I missing something? Why was 
rotate_transformer implemented this way?

Regards,
Adam